Control of tubulin gene expression in the parasitic protozoan Leishmania enriettii
Control of tubulin gene expression in the parasitic protozoan Leishmania enriettii
复制标题
寄生原生动物利什曼原虫中微管蛋白基因表达的控制
作者：
S. Landfear;D. Wirth
利什曼原虫属寄生原虫的生活史包括两种形态上不同的形式：(1)无鞭毛体，寄生在哺乳动物宿主的巨噬细胞内，不活动，只有残留的鞭毛；(2)前鞭毛体，生活在沙蝇媒介的肠道中的细胞外形式，具有高度运动性，拥有单一突出的鞭毛。在无鞭毛体向前鞭毛体的发育过程中，α-和β-微管蛋白的生物合成显著增加2，可能为鞭毛的合成和维持提供足够的微管蛋白。通过Northern印迹分析和体外翻译实验表明，恩氏利什曼原虫前鞭毛体中α-和β-tubuin基因的表达水平显著高于无鞭毛体。这些结果表明，与墨西哥利什曼原虫相比，Enriettii体内微管蛋白基因的表达控制在mRNA积累水平，而墨西哥利什曼原虫则被报道在翻译水平上控制基因表达。
The life cycle of parasitic protozoa of the genus Leishmania consists of two morphologically distinct forms1: (1) amastigotes, the form of the parasite that resides inside macrophages of the mammalian host, which are non-motile and possess only a residual flagellum; and (2) promastigotes, the extracellular forms that live in the gut of the sandfly vector, which are highly motile and possess a single prominent flagellum. During the developmental transformation of amastigotes to promastigotes, the biosynthesis of α-and β-tubulin proteins is dramatically increased2, presumably to provide sufficient tubulin for synthesis and maintenance of the flagellum. We show here that the level of α-and β-tubulin mRNA in Leishmania enrietti promastigotes is significantly greater than that in amastigotes, as determined by both Northern blot analysis and by in vitro translation of cellular RNA. These results show that the regulated expression of the tubulin genes is controlled at the level of mRNA accumulation in L. enriettii, by contrast with Leishmania mexicana, in which the control of gene expression has been reported to be at the level of translation.